A heat exchanger for an automobile air conditioning system and a method for manufacture of the same. The heat exchanger a plurality of refrigerant flowing tubes, a plurality of corrugated fins sandwiched between the tubes and a pair of header pipes liquid-tightly brazed and jointed to the opposite ends of the tubes respectively. Each of the header pipes is a hollow solid body produced by an extrusion of an aluminum material and having a flat section and a rounded section. The flat section includes a plurality of apertures for receiving the tubes and is thicker than the rounded section. Top and bottom support beams are not only brazed to the outermost corrugated fins but also jointed at their opposite ends to the flat sections of the header pipes. A plurality of brazing beads braze and liquid-tightly joint the opposite ends of the tubes to the first and second header pipes. The brazing beads are formed by melting in a brazing furnace a pair of brazing metal plates respectively interposed between the opposite ends of the tubes and the header pipes. This heat exchanger is prevented from burst, deformation and refrigerant leakage.